On the other hand, when sulphuric acid at different concentrations was used to impregnate the microalgae samples, the sugar yields were improved. The highest sugar yield (87%) was achieved when the steam explosion pretreatment was performed using 1.7% sulphuric acid and a temperature of 150 °C. Under these conditions, the individual sugar yields were above 80% for xylose and rhamnose,where as the glucose yield was 65%. This result indicates that the oligosaccharides composed of xylose and rhamnose units can bemore easily hydrolysed to its monomeric sugars than the gluco-oligosaccharide.